METHOD 5030C - PURGE-AND-TRAP FOR AQUEOUS SAMPLES · PDF file5030C - 1 Revision 3 May 2003...

5030C - 1 Revision 3May 2003

METHOD 5030C

PURGE-AND-TRAP FOR AQUEOUS SAMPLES

1.0 SCOPE AND APPLICATION

1.1 This method describes a purge-and-trap procedure for the analysis of volatile organiccompounds (VOCs) in aqueous samples and water miscible liquid samples. It also describes theanalysis of high concentration soil and waste sample extracts prepared in Method 5035. The gaschromatographic determinative steps are found in Methods 8015 and 8021. The method is alsoapplicable to GC/MS Method 8260. The following compounds have been evaluated using thissample preparation technique:

Compound CAS No.a Response Stability

Acetone 67-64-1 pp / ht hsAcetonitrile 75-05-8 pp ndAcrolein (Propenal) 107-02-8 pp msAcrylonitrile 107-13-1 pp hsAllyl alcohol 107-18-6 ht ndAllyl chloride 107-05-1 c mst-Amyl alcohol (TAA) 75-85-4 ht hst-Amyl ethyl ether (TAEE) 919-94-8 c / ht ndt-Amyl methyl ether (TAME) 994-05-8 c / ht hsBenzene 71-43-2 c hsBenzyl chloride 100-44-7 c ndBis(2-chloroethyl)sulfide 505-60-2 pp ndBromoacetone 598-31-2 pp ndBromochloromethane 74-97-5 c hsBromodichloromethane 75-27-4 c msBromoform 75-25-2 c hsBromomethane 74-83-9 c hvsn-Butanol 71-36-3 ht nd2-Butanone (MEK) 78-93-3 pp hvst-Butyl alcohol (TBA) 75-65-0 ht ndCarbon disulfide 75-15-0 pp hvsCarbon tetrachloride 56-23-5 c hvsChloral hydrate 302-17-0 pp ndChlorobenzene 108-90-7 c hvsChlorodibromomethane 124-48-1 c ndChloroethane 75-00-3 c ms2-Chloroethanol 107-07-3 pp nd2-Chloroethyl vinyl ether 110-75-8 c lsChloroform 67-66-3 c hs

(continued)



Chloromethane 74-87-3 c hvsChloroprene 126-99-8 c ndCrotonaldehyde 4170-30-3 pp nd1,2-Dibromo-3-chloropropane 96-12-8 pp ms1,2-Dibromoethane 106-93-4 c hsDibromomethane 74-95-3 c hs1,2-Dichlorobenzene 95-50-1 c hs1,3-Dichlorobenzene 541-73-1 c ms1,4-Dichlorobenzene 106-46-7 c mscis-1,4-Dichloro-2-butene 1476-11-5 c ndtrans-1,4-Dichloro-2-butene 110-57-6 pp lsDichlorodifluoromethane 75-71-8 c hs1,1-Dichloroethane 75-34-3 c hs1,2-Dichloroethane 107-06-2 c hs1,1-Dichloroethene 75-35-4 c hvscis-1,2-Dichloroethene 156-59-4 c hstrans-1,2-Dichloroethene 156-60-5 c ms1,2-Dichloropropane 78-87-5 c hs1,3-Dichloro-2-propanol 96-23-1 pp ndcis-1,3-Dichloropropene 10061-01-5 c lstrans-1,3-Dichloropropene 10061-02-6 c ls1,2,3,4-Diepoxybutane 1464-53-5 c ndDiethyl ether 60-29-7 c ndDiisopropyl ether (DIPE) 108-20-3 c / ht hs1,4-Dioxane 123-91-1 ht / pp ndEthylbenzene 100-41-4 c hvsEthylene oxide 75-21-8 pp ndEthyl methacrylate 97-63-2 c msEthyl tert-butyl ether (ETBE) 637-92-3 c / ht hsHexachlorobutadiene 87-68-3 c ms2-Hexanone 591-78-6 pp hvsIodomethane 74-88-4 c ndIsobutyl alcohol 78-83-1 ht / pp ndIsopropylbenzene 98-82-8 c msMalononitrile 109-77-3 pp ndMethacrylonitrile 126-98-7 pp hsMethylene chloride 75-09-2 c hsMethyl methacrylate 80-62-6 c ms4-Methyl-2-pentanone (MIBK) 108-10-1 pp msMethyl tert-butyl ether (MTBE) 1634-04-4 c / ht hsNaphthalene 91-20-3 c msNitrobenzene 98-95-3 c nd2-Nitropropane 79-46-9 c ndN-Nitroso-di-n-butylamine 924-16-3 pp nd

(continued)



Paraldehyde 123-63-7 pp nd2-Pentanone 107-87-9 pp nd2-Picoline 109-06-8 pp nd1-Propanol 71-23-8 ht / pp nd2-Propanol 67-63-0 ht / pp ndβ-Propiolactone 57-57-8 pp ndPropionitrile (ethyl cyanide) 107-12-0 ht ndn-Propylamine 107-10-8 c ndStyrene 100-42-5 c hvs1,1,1,2-Tetrachloroethane 630-20-6 c hs1,1,2,2-Tetrachloroethane 79-34-5 c ndTetrachloroethene 127-18-4 c msToluene 108-88-3 c hso-Toluidine 95-53-4 pp nd1,2,4-Trichlorobenzene 120-82-1 c hs1,1,1-Trichloroethane 71-55-6 c ms1,1,2-Trichloroethane 79-00-5 c hsTrichloroethene 79-01-6 c msTrichlorofluoromethane 75-69-4 c ls1,2,3-Trichloropropane 96-18-4 c lsVinyl acetate 108-05-4 c lsVinyl chloride 75-01-4 c hvso-Xylene 95-47-6 c hvsm-Xylene 108-38-3 c hvsp-Xylene 106-42-3 c hvs

a Chemical Abstract Service Registry Number

c = Adequate response by this techniqueht = Method analyte only when purged at elevated temperature, e.g., 80ECpp = Poor purging efficiency resulting in high quantitation limits. Use of an

alternative sample preparative method is strongly recommended. May be amenable topurging at elevated temperature.

nd = Not determinedhs = High stability in preserved water samples (> 60 days). Longer holding times may be

appropriate, see Method 5035, Appendix A, Table A.1 footnote and ref. 47 for additionalinformation

ms = Medium stability in preserved water samples (15 - 60 days). Longer holding times maybe appropriate, see Method 5035, Appendix A, Table A.1 footnote and ref. 47 foradditional information

ls = Low stability in preserved water samples (< 14 days), analyses should be performed assoon as possible. May be degraded if acid preserved.

hvs = Highly variable stability in preserved water samples. Longer holding times may beappropriate, see Method 5035, Appendix A, Table A.1 footnote and ref. 47 for additionalinformation.


1.2 Method 5030 can be used for most volatile organic compounds that have boiling pointsbelow 200EC and are insoluble or slightly soluble in water. Volatile water-soluble compounds canbe included in this analytical technique; however, quantitation limits (by GC or GC/MS) in somecases are approximately ten times higher with erratic precision because of poor purging efficiency.The method is also limited to compounds that elute as sharp peaks from a coated capillary column.Such compounds include low molecular weight halogenated hydrocarbons, aromatics, ketones,nitriles, acetates, acrylates, ethers, and sulfides. The purging efficiency can be improved for watersoluble analytes, e.g. ketones and alcohols, when purging at an elevated temperature of 80EC ascompared to 20E or 40EC.

Problems are often encountered with the analysis of methyl t-butyl ether (MTBE) and relatedfuel oxygenated compounds, both with the effectiveness of the analytical methods, and theevaluation of the resulting data. These fuel oxygenated compounds generally include: methyl t-butyl ether (MTBE), ethyl t-butyl ether (ETBE), t-amyl methyl ether (TAME), diisopropyl ether(DIPE), t-amyl ethyl ether (TAEE), t-amyl alcohol (TAA) and t-butyl alcohol (TBA) and can beclassified as volatile organics based on their boiling points and vapor pressures. However, themajor analytical problem is a result of the high solubility of some of these compounds in water,which makes it more difficult to use purge-and-trap (P&T) techniques for removing the compoundsfrom the environmental samples and introducing them into the analytical instrumentation (e.g., aGC or GC/MS system). Thus, using procedures that have been optimized for other, less water-soluble volatiles can potentially lead to significantly underestimating the concentrations of theoxygenates in the same samples.

EPA evaluated the performance of commonly used analytical methods in order to determinethe appropriate analytical conditions for measuring MTBE and other target oxygenates in aqueoussamples. (Method 5035, Appendix A, Refs. 49,50) With a minimal Method 5030 modification(heated 80°C rather than ambient temperature purge) and the choice of analytical column for thecommonly used volatiles Method 8260, the low-level concentration recoveries of MTBE and relatedoxygenates can be improved. The EPA study performance data indicated that using an RTX-Volatile capillary column with a heated rather than ambient temperature purge significantlyimproved the overall recovery of the alcohols, and consistent oxygenate recoveries were obtainedusing a heated purge and a DB-WAX capillary column. It is therefore recommended to use theheated at 80°C purge conditions along with a DB-WAX capillary column for optimum oxygenaterecovery in aqueous samples containing low-level concentrations, if alcohols, e.g., TBA and TAAare target analytes

1.3 Method 5030, in conjunction with Method 8015 (GC/FID), may be used for the analysisof the aliphatic hydrocarbon fraction in the light ends of total petroleum hydrocarbons, e.g.,gasoline. For the aromatic fraction (BTEX), use Method 5030 and Method 8021 (GC/PID). A totaldeterminative analysis of gasoline fractions may be obtained using Methods 8021 GC/PID) in serieswith Method 8015.

1.4 Water samples can be analyzed directly for volatile organic compounds bypurge-and-trap extraction and gas chromatography. Higher concentrations of these analytes inwater can be determined by direct injection of the sample into the chromatographic system or bydilution of the sample prior to the purge-and-trap process.

As with any preparative method for volatiles, samples should be screened to avoidcontamination of the purge-and-trap system by samples that contain very high concentrations ofpurgeable material above the calibration range of the low concentration method. In addition,because the sealed sample container cannot be opened to remove a sample aliquot without


compromising the integrity of the sample, multiple sample aliquots should be collected to allow forscreening and reanalysis.

1.5 Analysts should consult the disclaimer statement at the front of the manual and theinformation in Chapter Two for guidance on the intended flexibility in the choice of methods,apparatus, materials, reagents, and supplies, and on the responsibilities of the analyst fordemonstrating that the techniques employed are appropriate for the analytes of interest, in thematrix of interest, and at the levels of concern.

In addition, analysts and data users are advised that, except where explicitly specified in aregulation, the use of SW-846 methods is not mandatory in response to Federal testingrequirements. The information contained in this method is provided by EPA as guidance to be usedby the analyst and the regulated community in making judgments necessary to generate results thatmeet the data quality objectives for the intended application.

1.6 Use of this method is restricted to use by, or under supervision of, appropriatelyexperienced and trained laboratory analysts. Each analyst must demonstrate the ability to generateacceptable results with this method.

2.0 SUMMARY OF METHOD

2.1 Aqueous Samples: An inert gas is bubbled through a portion of the aqueous sampleat ambient temperature or an elevated temperature depending on the desired target analytes, andthe volatile components are efficiently transferred from the aqueous phase to the vapor phase. Thevapor is swept through a sorbent column where the volatile components are adsorbed. Afterpurging is completed, the sorbent column is heated and backflushed with inert gas to desorb thecomponents onto a gas chromatographic column.

2.2 High Concentration Extracts from Method 5035: An aliquot of the methanol extractprepared in Method 5035 is combined with organic free reagent water in the purging chamber. Itis then analyzed by purge-and-trap GC or GC/MS following the normal aqueous method.

3.0 DEFINITIONS

Refer to the SW-846 chapter of terms and acronyms for potentially applicable definitions.

4.0 INTERFERENCES

4.1 Impurities in the purge gas, and from organic compounds out-gassing from the plumbingahead of the trap, account for the majority of contamination problems. The analytical system mustbe demonstrated to be free from contamination under the conditions of the analysis by runninglaboratory reagent blanks. The use of non-polytetrafluoroethylene (non-PTFE) plastic coating,non-PTFE thread sealants, or flow controllers with rubber components in the purging device mustbe avoided, since such materials may out-gas organic compounds which will be concentrated inthe trap during the purge operation. These compounds will result in interferences or false positivesin the determinative step.


4.2 Samples can be contaminated by diffusion of volatile organics (particularly methylenechloride and fluorocarbons) through the septum seal of the sample vial during shipment andstorage. A trip blank prepared from an appropriate organic-free matrix and sample container, andcarried through sampling and handling protocols, serves as a check on such contamination.

4.3 Contamination by carryover can occur whenever high-concentration andlow-concentration samples are analyzed sequentially. Where practical, samples with unusuallyhigh concentrations of analytes should be followed by an analysis of organic-free reagent water tocheck for cross-contamination. If the target compounds present in an unusually concentratedsample are also found to be present in the subsequent samples, the analyst must demonstrate thatthe compounds are not due to carryover. Conversely, if those target compounds are not presentin the subsequent sample, then the analysis of organic-free reagent water is not necessary. Thetrap and other parts of the system are subject to contamination. Therefore, frequent bake-out andpurging of the entire system may be required.

4.4 The laboratory where volatiles analysis is performed should be completely free ofsolvents. Special precautions must be taken when analyzing for methylene chloride. The analyticaland sample storage areas should be isolated from all atmospheric sources of methylene chloride.Otherwise random background levels can result. Since methylene chloride can permeate throughPTFE tubing, all GC carrier gas lines and purge gas plumbing should be constructed of stainlesssteel or copper tubing. Laboratory workers' clothing previously exposed to methylene chloridefumes during common liquid/liquid extraction procedures can contribute to sample contamination.The presence of other organic solvents in the laboratory where volatile organics are analyzed canalso lead to random background levels and the same precautions must be taken.

5.0 SAFETY

This method does not address all safety issues associated with its use. The laboratory isresponsible for maintaining a safe work environment and a current awareness file of OSHAregulations regarding the safe handling of the chemicals included in this method. A reference fileof material safety data sheets (MSDSs) should be available to all personnel involved in theseanalyses.

6.0 EQUIPMENT AND SUPPLIES

The mention of trade names or commercial products in this manual is for illustrative purposesonly, and does not constitute an EPA endorsement or exclusive recommendation for use. Theproducts and instrument settings cited in SW-846 methods represent those products and settingsused during method development or subsequently evaluated by the Agency. Glassware, reagents,supplies, equipment, and settings other than those listed in this manual may be employed providedthat method performance appropriate for the intended application has been demonstrated anddocumented.

6.1 Sample containers

The specific sample containers required will depend on the purge-and-trap system to beemployed (see Sec. 6.2). Several systems are commercially available. Some systems employ40-mL clear vials with a special frit and equipped with two PTFE-faced silicone septa. Othersystems permit the use of any good quality glass vial that is large enough to contain the minimum


sample volume and can be sealed with a screw-cap containing a PTFE-faced silicone septum.Consult the purge-and-trap system manufacturer's instructions regarding the suitable specific vials,septa, caps, and mechanical agitation devices. Additional information on sample containers canbe found in Method 5035, Appendix A.

6.2 Purge-and-trap system

The purge-and- trap system consists of a unit that either manually or automatically samplesan appropriate volume, e.g., 5 mL or 25 mL from the vial, adds surrogates, matrix spikes andinternal standards (if applicable) to the sample and transfers the sample to the purge device, whichpurges the VOCs using an inert gas stream and also traps the released VOCs for subsequentdesorption into the gas chromatograph. Such systems are commercially available from severalsources and shall meet the following specifications.

6.2.1 The recommended purging chamber is designed to accept 5-mL samples witha water column at least 3 cm deep. The gaseous headspace between the water column andthe trap must have a total volume of less than 15 mL. The purge gas must pass through thewater column as finely divided bubbles with a diameter of less than 3 mm at the origin. Thepurge gas must be introduced no more than 5 mm from the base of the water column. Thesample purger, illustrated in Figure 1, meets these design criteria. Alternate sample purgedevices may be used, provided appropriate performance is demonstrated.

6.2.2 The trap used to develop this method was 25 cm long with an inside diameterof 0.267 cm. Starting from the inlet, the trap contains the following amounts of adsorbents:1/3 of 2,6-diphenylene oxide polymer, 1/3 of silica gel, and 1/3 of coconut charcoal. It isrecommended that 1.0 cm of methyl silicone-coated packing be inserted at the inlet to extendthe life of the trap (see Figures 2 and 3). If it is not necessary to analyze fordichlorodifluoromethane or other fluorocarbons of similar volatility, the charcoal can beeliminated and the polymer increased to fill 2/3 of the trap. If only compounds boiling above35EC are to be analyzed, both the silica gel and charcoal can be eliminated and the polymerincreased to fill the entire trap. Before initial use, the trap should be conditioned overnight at180EC by backflushing with an inert gas flow of at least 20 mL/min. Vent the trap effluent tothe hood, not to the analytical column. Prior to daily use, the trap should be conditioned for10 min at 180EC with backflushing. The trap may be vented to the analytical column duringdaily conditioning; however, the column must be run through the temperature program priorto analysis of samples.

6.2.3 The desorber must be capable of rapidly heating the trap to 180EC fordesorption. The polymer section of the trap should not be heated higher than 180EC, and theremaining sections should not exceed 220EC during bake-out mode. The desorber designillustrated in Figures 2 and 3 meet these criteria.

6.2.4 The purge-and-trap device may be assembled as a separate unit or may becoupled to a gas chromatograph, as shown in Figures 3 and 4.

6.2.5 Trap Packing Materials

6.2.5.1 2,6-Diphenylene oxide polymer - 60/80 mesh, chromatographic grade(Tenax GC or equivalent).


6.2.5.2 Methyl silicone packing - OV-1 (3%) on Chromosorb-W, 60/80 meshor equivalent.

6.2.5.3 Silica gel - 35/60 mesh, Davison, grade 15 or equivalent.

6.2.5.4 Coconut charcoal - Prepare from Barnebey Cheney, CA-580-26, orequivalent, by crushing through 26 mesh screen.

6.2.5.5 Alternate Trap Materials

A number of hydrophobic carbon molecular sieve and graphitized carbon blackmaterials have been developed. Various combinations of these materials have beenshown to provide retention properties similar to the Tenax\Silica gel\Carbon trap.Alternate trap construction with such materials is allowed, provided that the adsorptionand desorption characteristics obtained achieve method sensitivity and precision incomparison to the performance appropriate for the intended application.

6.2.5.5.1 The following alternatives have been shown to be viablefor most analytes of concern:

7.6-cm CarbopackTM B/1.3-cm CarbosieveTM S-IIIVOCARB 3000 - 10.0-cm CarbopackTM B/6.0-cm Carboxin TM 1000/1.0-cmCarboxinTM 1001VOCARB 4000 - 8.5-cm CarbopackTM C/10.0-cm CarbopackTM B/6.0-cmCarboxinTM 1000/1.0-cm CarboxinTM 1001

These combinations require rapid heating to desorption temperatures of 245ECto 270EC (follow manufacturer's instructions). At these increased temperatures,catalytic and thermal decomposition of analytes has been reported. TheVOCARB 4000 combination has also been demonstrated to catalytically breakdown 2-chloroethyl vinyl ether, and to partially decompose 2,2-dichloropropane.Bromoform and bromomethane have shown some thermal decomposition.

6.2.5.5.2 The amount of thermal decomposition products formedmust be routinely tracked by daily monitoring of the formation of chloromethaneand bromomethane. A daily check standard containing surrogates, internalstandards, and 20 µg/L bromoform must be analyzed prior to the analysis of thedaily check standard. If levels of chloromethane or bromomethane exceed 0.5µg/L, then the trap may be too contaminated with salts or tightly boundcontamination for analysis to continue. The trap must be replaced and thesystem recalibrated.

NOTE: Even newly constructed traps may have become contaminatedprior to their first use from airborne vapors. These highlyadsorptive materials must be kept tightly sealed in an area ofminimum organic vapor contamination.

6.3 Heater or heated oil bath - capable of maintaining the purging chamber to within 1EC,over a temperature range from ambient to 100EC.


6.4 Capillary GC Columns - Any GC column that meets the performance criteria of thedeterminative method may be used. See the specific determinative method for recommendedcolumns, conditions and retention times.

6.4.1 The wide-bore columns have the capacity to accept the standard gas flows fromthe trap during thermal desorption, and chromatography can begin with the onset of thermaldesorption. Depending on the pumping capacity of the MS, an additional interface betweenthe end of the column and the MS may be required. An open split interface , an all-glass jetseparator, or a cryogenic (Sec. 6.4.2) device are acceptable interfaces. The type of interfaceand its adjustments can have a significant impact on the detection limits of the method. Otherinterfaces can be used if the performance criteria described in this method can be achieved.

6.4.2 A system using a narrow-bore column will require lower gas flows ofapproximately 2 - 4 mL/minute. Because of these low desorption flows, early eluting analytesneed to be refocused to elute in a narrow band. This refocusing may be carried out by usinga cryogenic interface. This type of interface usually uses liquid nitrogen to condense thedesorbed sample components in a narrow band on an uncoated fused silica precolumn.When all components have been desorbed from the trap, the interface is rapidly heated undera stream of carrier gas to transfer the analytes to the analytical column. The end of theanalytical column should be placed within a few mm of the MS ion source. A potentialproblem with this interface is blockage of the interface by ice caused by desorbing water fromthe trap. This condition will result in a major loss in sensitivity and chromatographicresolution. Low surrogate compound recoveries can be a sign that this is occurring.

6.5 Syringe and syringe valves

6.5.1 Microsyringes - 10-µL, 25-µL, 100-µL, 250-µL, 500-µL, and 1,000-µL. Thesesyringes should be equipped with a 20-gauge (0.006 in ID) needle having a length sufficientto extend from the sample inlet to within 1 cm of the glass frit in the purging device. Theneedle length will depend upon the dimensions of the purging device employed.

6.5.2 Syringe valve - Two-way, with Luer ends (three each), if applicable to the purgingdevice.

6.5.3 Two 5-mL glass hypodermic syringes with Luer-Lok tip (other sizes areacceptable depending on sample volume used).

6.6 Miscellaneous

6.6.1 40-mL, screw-cap, PTFE lined, septum-sealed. Examine each vial prior to useto ensure that the vial has a flat, uniform sealing surface.

6.6.2 Volumetric flasks, Class A - 10-mL and 100-mL, with ground-glass stoppers.

7.0 REAGENTS AND STANDARDS

7.1 Reagent grade chemicals must be used in all tests. Unless otherwise indicated, it isintended that all reagents conform to the specifications of the Committee on Analytical Reagentsof the American Chemical Society, where such specifications are available. Other grades may be


used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its usewithout lessening the accuracy of the determination.

7.2 Organic-free reagent water - All references to water in this method refer to organic-freereagent water, as defined in Chapter One.

7.3 Sample preservative

7.3.1 For determination as to whether sample preservation is necessary and forselection of appropriate preservation options, see Method 5035, Appendix A.

7.3.2 Sodium bisulfate, NaHSO4 - ACS reagent grade or equivalent.

7.3.3 Hydrochloric acid, concentrated, HCl - ACS reagent grade or equivalent.

CAUTION: If samples containing MTBE, TAME, ETBE or other fuel ethers have been acidpreserved with either sodium bisulfate (Sec. 7.3.2) or hydrochloric acid (Sec.7.3.3), and will be analyzed by purging at elevated temperatures, these samplesmust be adjusted to pH >10 with trisodium phosphate dodecahydrate (TSP)(Sec. 7.3.4) prior to initiation of the analysis.

7.3.4 Trisodium phosphate dodecahydrate (TSP), Na3PO4C12H2O - ACS reagentgrade or equivalent (for fuel oxygenates) (Ref. 5).

7.3.5 The preservative, if necessary, should be added to the vial prior to shipment tothe field, and must be present in the vial prior to adding the sample.

CAUTION: If a dechlorinating agent and acid are both added as preservatives, the samplesmust be dechlorinated first and then acidified.

7.4 See the determinative method and Method 5000 for guidance on internal standards andsurrogates to be employed in this procedure. The recommended surrogates are4-bromofluorobenzene, 1,4-difluorobenzene, 1,2-dichloroethane-d4, and toluene-d8. Othercompounds may be used as surrogates, depending upon the analysis requirements and the specifictarget analytes. The recommended internal standards are chlorobenzene-d5, 1,4-dichlorobenzene-d4, and fluorobenzene. Other compounds may be used as internal standards as long as they haveretention times similar to the target analytes being detected.

8.0 SAMPLE COLLECTION, PRESERVATION, AND STORAGE

8.1 Refer to the introductory material in this chapter, Organic Analytes, Sec. 4.1, andMethod 5035, Appendix A for general sample collection information. Samples should be stored incapped vials, with minimum headspace, at 4EC or less in an area free of solvent fumes. The sizeof any bubble caused by degassing upon cooling the sample should not exceed 5 - 6 mm. Whena bubble is present, also observe the cap and septum to ensure that a proper seal was made attime of sampling. Is there any evidence of leakage? If the sample was improperly sealed, thesample should be discarded.


8.2 Preparation of sample vials

The specific preparation procedures for sample vials will depend on the desired targetanalytes as specified in the project planning documents. Depending on the desired class of targetanalytes sample preservation may or may not be necessary and the analytical holding time will bebased on whether a preservative is present. Sample vials should be prepared in a fixed laboratoryor other controlled environment, sealed, and shipped to the field location. Gloves should be wornduring the preparation steps. More detailed information on additional options for the preparationof sample vials can be found in Method 5035, Appendix A.

8.3 Sample collection

Collect the sample according to the procedures outlined in the sampling plan. As with anysampling procedure for volatiles, care must be taken to minimize the disturbance of the sample inorder to minimize the loss of the volatile components. Since only one analysis can be peformedon one sample vial, multiple vials should be collected especially for those samples designated forscreening and QC analyses. For some specific project situations, VOA compositing can be usedto achieve the project’s data quality objectives. Samples may only be composited if the laboratory’squantitation and detection levels are adequate for the number of samples being composited (up toa maximum of five). The compositing must be done in the laboratory (See Note after Sec. 11.2.4.5).Always wear gloves whenever handling vials prior to and during sample collection. More detailedinformation and additional sample collection options can be found in Method 5035, Appendix A.

8.4 Sample handling and shipment

All samples for volatiles analysis should be cooled to approximately 4EC, packed inappropriate containers, and shipped to the laboratory on ice, as described in the sampling plan.See Method 5035, Appendix A for additional sample handling options.

8.5 Sample storage

8.5.1 Once in the laboratory, store samples at the recommended temperature untilanalysis (refer to Method 5035, Appendix A for additional sample storage information). Thesample storage area should be free of organic solvent vapors.

8.5.2 All samples should be analyzed as soon as practical, and within the designatedholding time from collection. Generally, a holding time of 14 days from sample collection willapply to most applications. However, see the cautionary notes in Method 5035, Appendix A,Table A-1 and the Table of Analytes in Sec. 1.1 of this method pertaining to certain compoundclasses and applicable preservation options that may affect target analyte stability andanalytical holding times. A longer holding time may be appropriate if it can be demonstratedthat the reported VOC concentrations are not adversely affected by preservation, storage andanalyses performed outside the recommended holding times. Otherwise without thisperformance demonstration, samples not analyzed within the recommended holding timemust be noted and the data should be considered as minimum values.

9.0 QUALITY CONTROL

9.1 Refer to Chapter One for guidance on quality assurance (QA) and quality control (QC)protocols. Each laboratory should maintain a formal quality assurance program. The laboratory


should also maintain records to document the quality of the data generated. All data sheets andquality control data should be maintained for reference or inspection. When inconsistencies existbetween QC guidelines, method-specific QC criteria take precedence over both technique-specificcriteria and those criteria given in Chapter One, and technique-specific QC criteria take precedenceover the criteria in Chapter One.

9.2 Before processing any samples, the analyst should demonstrate that all parts of theequipment in contact with the sample and reagents are interference-free. This is accomplishedthrough the analysis of a method blank. Each time samples are extracted, cleaned up, andanalyzed, and when there is a change in reagents, a method blank should be prepared andanalyzed for the compounds of interest as a safeguard against chronic laboratory contamination.

9.3 Any method blanks, matrix spike samples, or replicate samples should be subjected tothe same analytical procedures (Sec. 11.0) as those used on actual samples.

9.4 Initial Demonstration of Proficiency - Each laboratory must demonstrate initial proficiencywith each sample preparation and determinative method combination it utilizes, by generating dataof acceptable accuracy and precision for target analytes in a clean matrix. The laboratory must alsorepeat the following operations whenever new staff are trained or significant changes ininstrumentation are made. See Methods 5000 and 8000 for information on how to accomplish thisdemonstration.

9.5 Sample Quality Control for Preparation and Analysis - See Methods 5000 and 8000 forprocedures to follow to demonstrate acceptable continuing performance on each set of samplesto be analyzed. This includes the method blank, either a matrix spike/matrix spike duplicate or amatrix spike and duplicate sample analysis, a laboratory control sample (LCS) and the addition ofsurrogates to each sample and QC sample.

9.6 It is recommended that the laboratory adopt additional quality assurance practices foruse with this method. The specific practices that are most productive depend upon the needs ofthe laboratory and the nature of the samples. Whenever possible, the laboratory should analyzestandard reference materials and participate in relevant performance evaluation studies.

9.7 The laboratory should have quality control procedures to make sure that sample integrityis not compromised during the sample collection and sample handling process, e.g., making surethat septa and vial caps do not leak, etc. In addition, it would be advisable for the laboratory tomonitor the internal standard (IS) area counts for all samples, since leaks attributed to a poor sealwith the vial caps and septa will be evident by low IS area counts. Sample containers and dataresults for instances where low IS area counts are observed and leaks are suspected, should bediscarded.

10.0 CALIBRATION AND STANDARDIZATION

See Sec. 11.0 for information on calibration and standardization and refer to the appropriatedeterminative method for additional calibration and standardization procedures.


11.0 PROCEDURE

11.1 The purge-and-trap technique for aqueous samples is found in Sec. 11.2 and guidancefor analysis of solvent extracts from the High Concentration Method in Method 5035 is found in Sec.11.3. The gas chromatographic determinative steps are found in Methods 8015 and 8021. Themethod is also applicable to GC/MS Method 8260. For the analysis of gasoline, use Method 8021with GC/PID for BTEX in series with Method 8015 with the GC/FID detector for hydrocarbons.

11.2 This section provides guidance on the analysis of aqueous samples and samples thatare water miscible, by purge-and-trap analysis.

11.2.1 Initial set-up

Prior to using this introduction technique for any GC or GC/MS method, the systemmust be calibrated. General calibration procedures are discussed in Method 8000, while thedeterminative methods and Method 5000 provide specific information on calibration andpreparation of standards. Normally, external standard calibration is preferred for the GCmethods (non-MS detection) because of possible interference problems with internalstandards. If interferences are not a problem, or when a GC/MS method is used, internalstandard calibration may be employed. The GC/MS methods require instrument tuning priorto proceeding with calibration.

11.2.1.1 Assemble a purge-and-trap device that meets the specification in Sec.6.2. Condition the Tenax trap overnight at 180EC (condition other traps at themanufacturers recommended temperature) in the purge mode with an inert gas flowof at least 20 mL/min. Prior to use, condition the trap daily for 10 min whilebackflushing at 180EC with the column at 220EC.

11.2.1.2 Connect the purge-and-trap device to a gas chromatograph or gaschromatograph/mass spectrometer system.

11.2.1.3 Prepare the final solutions containing the required concentrations ofcalibration standards, including surrogate standards and internal standards, andtransfer 5 mL to the purge device using either an automated sampler (Sec. 11.2.1.3.1)or manually using a syringe (Sec. 11.2.1.3.2)

NOTE: If sample volumes other than 5 mL are being used, e.g., 25-mL samples,then the calibration standards used must be of the same correspondingvolume.

11.2.1.3.1 When using an autosampler, prepare the calibration standard ina volumetric flask and transfer it to a vial and seal it. Place the sample vial inthe instrument carousel according to the manufacturer's instructions. Withoutdisturbing the hermetic seal on the sample vial, a specific sample volume iswithdrawn (usually 5 or 25 mL) and placed into the purging vessel along with theaddition of internal standards and surrogate compounds using an automatedsampler.

11.2.1.3.2 The organic-free reagent water is added to the purging deviceusing a 5-mL glass syringe (a 10-mL or 25-mL syringe may be used if preferred)fitted with a 15-cm 20-gauge needle. The needle is inserted through the sample


inlet shown in Figure 1. The internal diameter of the 14-gauge needle that formsthe sample inlet will permit insertion of the 20-gauge needle. Next, using a 10-µL or 25-µL micro-syringe equipped with a long needle (Sec. 6.5.1), take avolume of the secondary dilution solution containing appropriate concentrationsof the calibration standards. Add the aliquot of calibration solution directly to theorganic-free reagent water in the purging device by inserting the needle throughthe sample inlet. When discharging the contents of the micro-syringe, be surethat the end of the syringe needle is well beneath the surface of the organic-freereagent water. Similarly, add 10.0 µL of the internal standard solution. Closethe 2-way syringe valve at the sample inlet. (The calibration standard, internalstandard and surrogate standard may be added directly to the organic freereagent water in the syringe prior to transferring the water to the purging device,see Sec. 11.2.4.7).

11.2.1.4 Follow the purge-and-trap analysis as outlined in Sec. 11.2.4.

11.2.1.5 Calculate calibration factors (CF) or response factors (RF) for eachanalyte of interest using the procedures described in Method 8000. Calculate theaverage CF (external standards) or RF (internal standards) for each compound, asdescribed in Method 8000. Evaluate the linearity of the calibration data, or chooseanother calibration model, as described in Method 8000 and the specific determinativemethod.

11.2.1.6 If the purge-and-trap procedure is used with either Method 8021 orMethod 8260, evaluate the response for the following four compounds:chloromethane; 1,1-dichloroethane; bromoform; and 1,1,2,2-tetrachloroethane. Theyare used to check for proper purge flow and to check for degradation caused bycontaminated lines or active sites in the system.

11.2.1.6.1 Chloromethane: This compound is the most likelycompound to be lost if the purge flow is too fast.

11.2.1.6.2 Bromoform: This compound is one of the compoundsmost likely to be purged very poorly if the purge flow is too slow. Cold spotsand/or active sites in the transfer lines may adversely affect response.

11.2.1.6.3 1,1,2,2-Tetrachloroethane and 1,1-dichloroethane: Thesecompounds are degraded by contaminated transfer lines in purge-and-trapsystems and/or active sites in trapping materials.

11.2.1.7 When analyzing for very late eluting compounds with Method 8021 (i.e.,hexachlorobutadiene, 1,2,3-trichlorobenzene, etc.), cross-contamination and memoryeffects from a high concentration sample or even the standard are a commonproblem. Extra rinsing of the purge vessel after analysis normally corrects this. Thenewer purge-and-trap systems often overcome this problem with better bake-out ofthe system following the purge-and-trap process. Also, the charcoal traps retain lessmoisture and decrease the problem.


11.2.2 Calibration verification (see appropriate determinative method)

Refer to Method 8000 for details on calibration verification. A single standard near themid-point of calibration range or the action level is used for verification. This standard maybe prepared using either an automated sampler or manually using a syringe.

11.2.2.1 When using an autosampler, prepare the calibration standard in avolumetric flask and transfer it to a vial and seal it. Place the sample vial in theinstrument carousel according to the manufacturer's instructions. Without disturbingthe hermetic seal on the sample vial, a specific sample volume is withdrawn (usually5 or 25 mL) and placed into the purging vessel along with the addition of internalstandards and surrogate compounds using an automated sampler.

11.2.2.2 To prepare a calibration standard, inject an appropriate volume of aprimary dilution standard to an aliquot of organic free reagent water in a volumetricflask, a gas tight syringe, or to a purge device, and inject an appropriate amount ofinternal standard to the organic free reagent water. Be sure the same amount ofinternal standard is added to each standard and sample. The volume of organic freereagent water used for calibration must be the same volume that is used for sampleanalysis (normally 5 mL). The surrogate and internal standard solutions must beadded with a syringe needle long enough to ensure addition below the surface of thewater. Assemble the purge-and-trap device as outlined in 6.2. Follow the guidancefor the purge-and-trap procedure in Sec. 11.2.4. Ongoing GC or GC/MS calibrationcriteria must be met as specified in Method 8000 before analyzing samples.

11.2.3 Sample screening

11.2.3.1 It is highly recommended that all samples be screened prior to thepurge-and-trap GC or GC/MS analysis. Samples may contain higher than expectedquantities of purgeable organics that will contaminate the purge-and-trap system,thereby requiring extensive cleanup and instrument maintenance. Screening of thesample prior to purge-and-trap analysis may provide guidance on whether sampledilution is necessary.

11.2.3.2 SW-846 contains three screening techniques that may be utilized: theautomated headspace sampler (Method 5021) connected to a gas chromatographequipped with a photoionization detector in series with an electrolytic conductivitydetector; screening with a portable photoionization detector (PID) (Method 3815) or;extraction of the samples with hexadecane (Method 3820) and analysis of the extracton a gas chromatograph equipped with a flame ionization detector and/or electroncapture detector. In addition, other appropriate screening techniques may be employedusing the analyst’s professional judgment.

11.2.4 Sample introduction and purging

11.2.4.1 All samples and standard solutions must be allowed to warm toambient temperature before analysis. Suspended particulates in volatile organicsamples should be allowed to settle and are not subsampled.

11.2.4.2 Assemble the purge-and-trap device. The operating conditions for theGC and GC/MS are given in Sec. 11.0 of the specific determinative method to be


employed. Whole oven cooling may be needed for certain GC columns and/or certainGC/MS systems to achieve adequate resolution of the gases. Normally a 30-meterwide-bore column will require cooling the GC oven to 25EC or below for resolution of thegases.

11.2.4.3 GC or GC/MS calibration verification criteria must be met (Method8000) before analyzing samples.

11.2.4.4 Adjust the purge gas flow rate (nitrogen or helium) to 25-40 mL/min(also see Table 1 for guidance on specific analyte groups), and the operatingtemperature (if other than ambient) on the purge-and-trap device. Optimize the flow rateto provide the best response for chloromethane and bromoform, if these compounds areanalytes. Excessive flow rate reduces chloromethane response, whereas insufficientflow reduces bromoform response. All samples and standards should be run using thesame purge gas flow rate and at the same temperature.

11.2.4.5 Introduction of the sample into the purging vessel can be done usingeither an automated sampler (Sec. 11.2.4.5.1) or a manual procedure using a syringe(Sec. 11.2.4.5.2).

11.2.4.5.1 Place the sample vial in the instrument carousel according to themanufacturer's instructions. Without disturbing the hermetic seal on the samplevial, a specific sample volume is withdrawn (usually 5 or 25 mL) and placed intothe purging vessel along with the addition of internal standards and surrogatecompounds using an automated sampler.

11.2.4.5.2 Alternatively, a gas tight syringe may be inserted through theseptum of the vial to withdraw the sample. Or when the sample size taken isgreater than 5 mL, remove the plunger from an appropriately sized syringe andattach a closed syringe valve. If lower detection limits are required, use a 25-mLsyringe. Open the sample vial, and carefully pour the sample into the syringebarrel to just short of overflowing. Replace the syringe plunger and compress thesample. Open the syringe valve and vent any residual air while adjusting thesample volume to 5.0 mL or 25.0 mL. This process of taking an aliquot destroysthe validity of the liquid sample for future analysis; therefore, if there is only oneVOA vial, the analyst should fill a second syringe at this time to protect againstpossible loss of sample integrity. This second sample is maintained only untilthe analyst has determined that the first sample has been analyzed properly.If a second analysis is needed, it should be analyzed within 24 hours. Caremust be taken to prevent air from leaking into the syringe.

NOTE: Compositing Samples: VOA compositing must be performed in aclosed system using an air-tight syringe. This is accomplished bywithdrawing equal volumes of water from each discrete sampleutilizing a syringe large enough to hold the exact volume to be used forsample analysis. For example, using a small needle to vent thesample vial, withdraw 1.25 mL through the septum from each of 4sample vials thus collecting 5 mLs of water in the syringe to beanalyzed for a 1:4 composite.


11.2.4.6 For the sample selected for matrix spiking, add the matrix spikingsolution described in the Reagents Section of Method 5000, either manually, orautomatically, following the manufacturer's instructions. The concentration of thespiking solution and the amount added should be established as described in theQuality Control Section of Method 8000.

11.2.4.7 When sample dilution is necessary, samples can be diluted beforepurging using the autosampler device. Alternatively, manual dilutions can be performeddirectly in the 5-mL syringe that has been filled with reagent water through the use ofappropriate microliter syringes, or with volumetric glassware, as appropriate. All sampledilution steps must be performed without delays until the diluted sample is in a gas-tightsyringe.

11.2.4.7.1 For dilutions prepared in volumetric flasks, 10-mL to 100-mL volumes are recommended. Select the volumetric flask that will allow for thenecessary dilution of the desired target analytes within the upper limit of thecalibration curve. Intermediate dilutions may be necessary for extremely largedilutions.

11.2.4.7.2 Calculate the approximate volume of organic-free reagentwater to be added to the volumetric flask selected and add slightly less than thisquantity of organic-free reagent water to the flask.

11.2.4.7.3 Inject the proper volume of sample from the syringeprepared in Sec. 11.2.4.5 into the flask. Aliquots of less than 1 mL are notrecommended. Dilute the sample to the mark with organic-free reagent water.Cap the flask, invert, and shake three times. Repeat the above procedure foradditional dilutions.

11.2.4.7.4 Fill a 5-mL syringe with the diluted sample as in Sec.11.2.4.5.

11.2.4.8 Add 10.0 µL of surrogate spiking solution (found in each determinativemethod, Sec. 11.0) and, if applicable, 10.0 µL of internal standard spiking solutionthrough the valve bore of the syringe; then close the valve. The surrogate and internalstandards may be mixed and added as a single spiking solution. Matrix spikingsolutions, if indicated, should be added (10.0 µL) to the sample at this time.

11.2.4.9 Attach the syringe-syringe valve assembly to the syringe valve on thepurging device. Open the syringe valves and inject the sample into the purgingchamber.

11.2.4.10 Close both valves and purge the sample for the time and at thetemperature included in Table 1. For GC/MS analysis using Method 8260, purge timeis usually 11 minutes at ambient temperature.

11.2.5 Sample desorption

The procedures employed for sample desorption depend on the type of GC interfaceused. Procedures for non-cryogenic and cryogenic interfaces are described below. Analysts


should also consult the instructions from the manufacturer of the purge-and-trap system andthe supplier of the trap packing material.

11.2.5.1 Non-cryogenic interface - After the recommended 11-minute purge (seeTable 1 for guidance on purge times for specific analyte groups), place the purge-and-trap system in the desorb mode and preheat the trap to 180EC (or other temperaturerecommended for the specific trap packing material) without a flow of carrier gaspassing through the trap.

NOTE: Some purge-and-trap systems are capable of performing a moisture removalstep (e.g., dry purge) which can eliminate excess moisture from the trap andgas lines by purging the trap just prior to the desorption step. However, theutility of a moisture removal step depends on the nature of the trap packingmaterial. In general, when using a carbon-based, hydrophobic trap packing,this step may prevent moisture from entering the GC system and affectingchromatography, but may require that the trap be cooled to keep thetemperature at or below 25EC. However, for packings that are lesshydrophobic or hydrophilic (such as silica gel), a moisture removal step mayactually create more significant problems, including loss of sensitivity, poorchromatography, and premature failure of the trap packing material, throughthe release of increasing amounts of water into the GC system during thecourse of an analytical shift. The problem may be evident as erraticresponses for the early-eluting internal standards and surrogates over thecourse of the day. Optimum results may be achieved through the properchoices of: the moisture control device, the trap packing material, traptemperature during moisture removal, and carrier gas flow. The use of trapback pressure control may also be necessary. Consult instructions fromboth the manufacturer of the purge-and-trap system and the supplier of thetrap packing material before employing a moisture removal step.

Start the flow of the carrier gas, begin the GC temperature program, and startGC data acquisition. The carrier gas flow rate will depend on the trap employed. A flowrate of 15 mL/min is used for the standard silica gel trap (Sec. 4.6.2), while 10 mL/minmay be adequate for other traps. Continue the carrier gas flow for about 4 min, or asrecommended by the manufacturer. Desorption times as low as 1.5 min may beadequate for analytes in Method 8015.

11.2.5.2 Cryogenic interface - After the 11 minute purge, place thepurge-and-trap system in the desorb mode, make sure the cryogenic interface is -150ECor lower, and rapidly heat the trap to 180EC (temperature may vary depending on thetrap material) while backflushing with an inert gas at 4 mL/minute for about 5 minutes(1.5 min is normally adequate for analytes in Method 8015). At the end of the 5-minutedesorption cycle, rapidly heat the cryogenic trap to 250EC; simultaneously begin thetemperature program of the gas chromatograph and start the data acquisition.

11.2.6 Trap Reconditioning

11.2.6.1 After desorbing the sample, recondition the trap by returning thepurge-and-trap device to the purge mode. Wait 15 seconds, then close the syringevalve on the purging device to begin gas flow through the trap. The trap temperatureshould be maintained at 180EC for Methods 8021 and 8260, and 210EC for Method


8015. Trap temperatures up to 220EC may be employed. However, the highertemperatures will shorten the useful life of the trap. (Trap temperatures may varydepending on the trap material). After approximately 7 min, turn off the trap heater andopen the syringe valve to stop the gas flow through the trap. When cool, the trap isready for the next sample.

11.2.6.2 While the trap is being desorbed into the gas chromatograph, emptythe purging chamber. Wash the chamber with a minimum of two 5 mL flushes oforganic free reagent water (or methanol followed by organic free reagent water) to avoidcarryover of volatile organics into subsequent analyses.

11.2.7 Interpretation and calculation of data

11.2.7.1 Perform qualitative and quantitative analysis following the guidancegiven in the determinative method and Method 8000. If the initial analysis of a sampleor a dilution of the sample has a concentration of analytes that exceeds the initialcalibration range, the sample must be reanalyzed at a higher dilution. When a sampleis analyzed that has saturated response from a compound, this analysis must befollowed by the analysis of organic free reagent water. If the blank analysis is not freeof interferences, the system must be decontaminated. Sample analysis should notresume until a blank can meet the organic-free reagent water criteria described inChapter One.

11.2.7.2 All dilutions should keep the response of the major constituents(previously saturated peaks) in the upper half of the linear range of the curve. Proceedto Method 8000 and the specific determinative method for details on calculating analyteresponse.

11.2.8 Analysis of water-miscible liquids

11.2.8.1 Water-miscible liquids are analyzed as water samples after first dilutingthem at least 50-fold with organic-free reagent water.

11.2.8.2 Initial and serial dilutions can be prepared by pipetting 2 mL of thesample into a 100-mL volumetric flask and diluting to volume with organic-free reagentwater. Transfer immediately to a 5-mL gas-tight syringe.

11.2.8.3 Alternatively, prepare dilutions directly in a 5-mL syringe filled withorganic-free reagent water by adding at least 20.0 µL, but not more than 100.0 µL ofliquid sample. The sample is ready for addition of surrogate and, if applicable, internaland matrix spiking standards.

11.2.9 Analysis of water soluble analytes

11.2.9.1 Many highly water soluble analytes, e.g., ketones, alcohols, aldehydes,and 1,4-dioxane, which are listed as poor purgers (pp) or high temperature purgers (ht)in the table in Sec. 1.1 can be analyzed using this method, if the purge-and-trapprocedure is performed at an elevated temperature, usually at 80EC.

11.2.9.2 If aqueous samples need to be analyzed for fuel oxygenates includingthe alcohols, e.g. t-butyl alcohol (TBA) and t-amyl alcohol (TAA), they must be


adjusted to pH >10 with trisodium phosphate dodecahydrate (TSP) (Sec. 7.3.4) priorto initiation of the purge cycle.

11.2.9.3 the following purge-and-trap cycle conditions are a recommendedstarting point for method optimization:

Use hydrophobic trapping materials to prevent excessive moisture collection inthe trap

Varian Archon autosampler (or equivalent) preheated to 80EC for 3 minutes.

Tekmar 3000 purge-and-trap concentrator (or equivalent)Purge time: 7min.Dry purge time: 3 min.Desorb time: 3 min.Bake time: 3min.

11.3 This section provides guidance on the analysis of solvent extracts from HighConcentration Samples prepared by Method 5035.

11.3.1 The GC or GC/MS system should be set up as in Sec. 11.0 of the specificdeterminative method. This should be done prior to the addition of the solvent extract toorganic-free reagent water.

11.3.2 Table 2 can be used to determine the volume of solvent extract to add to the 5mL of organic-free reagent water for analysis. If a screening procedure was followed, use theestimated concentration to determine the appropriate volume. Otherwise, estimate theconcentration range of the sample from the low-concentration analysis to determine theappropriate volume. If the sample was submitted as a high-concentration sample, start with100.0 µL. All dilutions must keep the response of the major constituents (previously saturatedpeaks) in the upper half of the linear range of the curve.

11.3.3 Remove the plunger from a 5.0-mL Luer-lok type syringe equipped with a syringevalve and fill until overflowing with organic-free reagent water. Replace the plunger andcompress the water to vent trapped air. Adjust the volume to 4.9 mL. Pull the plunger backto 5.0 mL to allow volume for the addition of the sample extract and of standards. Add 10.0µL of internal standard solution. Also add the volume of solvent extract determined in Sec.11.3.2 and a volume of the same solvent used in Method 5035 to total 100.0 µL (excludingmethanol in standards).

11.3.4 Attach the syringe-syringe valve assembly to the syringe valve on the purgingdevice. Open the syringe valve and inject the water/methanol sample into the purgingchamber.

11.3.5 Proceed with the analysis as outlined in the specific determinative method.Analyze all reagent blanks on the same instrument as that used for the samples. Thestandards and blanks should also contain 100.0 µL of methanol to simulate the sampleconditions.


11.4 Sample analysis

The samples prepared by this method may be analyzed by Methods 8015, 8021, and 8260.Refer to these methods for appropriate analysis conditions. For the analysis of gasoline, useMethod 8021 with GC/PID for BTEX in series with Method 8015 with the GC/FID detector forhydrocarbons.

12.0 DATA ANALYSIS AND CALCULATIONS

There are no data analysis and calculation steps directly associated with this procedure.Follow the directions given in the determinative method.

13.0 METHOD PERFORMANCE

Refer to the determinative methods for performance data examples and guidance.

14.0 POLLUTION PREVENTION

14.1 Pollution prevention encompasses any technique that reduces or eliminates the quantityand/or toxicity of waste at the point of generation. Numerous opportunities for pollution preventionexist in laboratory operation. The EPA has established a preferred hierarchy of environmentalmanagement techniques that places pollution prevention as the management option of first choice.Whenever feasible, laboratory personnel should use pollution prevention techniques to addresstheir waste generation. When wastes cannot be feasibly reduced at the source, the Agencyrecommends recycling as the next best option.

14.2 For information about pollution prevention that may be applicable to laboratories andresearch institutions consult Less is Better: Laboratory Chemical Management for Waste Reductionavailable from the American Chemical Society's Department of Government Relations and SciencePolicy, 1155 16th St., N.W. Washington, D.C. 20036, (202) 872-4477.

15.0 WASTE MANAGEMENT

The Environmental Protection Agency requires that laboratory waste management practicesbe conducted consistent with all applicable rules and regulations. The Agency urges laboratoriesto protect the air, water, and land by minimizing and controlling all releases from hoods and benchoperations, complying with the letter and spirit of any sewer discharge permits and regulations, andby complying with all solid and hazardous waste regulations, particularly the hazardous wasteidentification rules and land disposal restrictions. For further information on waste management,consult The Waste Management Manual for Laboratory Personnel available from the AmericanChemical Society at the address listed in Sec. 14.2.

16.0 REFERENCES

1. U.S. EPA 40 CFR Part 136, "Guidelines Establishing Test Procedures for the Analysis ofPollutants Under the Clean Water Act; Final Rule and Interim Final Rule and Proposed Rule,"


October 26, 1984.

2. Bellar, T., "Measurement of Volatile Organic Compounds in Soils Using ModifiedPurge-and-Trap and Capillary Gas Chromatography/Mass Spectrometry", U.S. EnvironmentalProtection Agency, Environmental Monitoring Systems Laboratory, Cincinnati, OH, November,1991.

3. USEPA OSW, "Development and Evaluation of Methods for the Analysis of MTBE,"September 17, 2001.

4. USEPA OUST, Environmental Fact Sheet: Analytical Methods for Fuel Oxygenates, EPA 510-F-03-001, April, 2003, http://www.epa.gov/OUST/mtbe/omethods.pdf.

5. White, H., Lesnik, B., and Wilson, J. T., “Analytical Methods for Fuel Oxygenates”, LUSTLine(Bulletin #42), October, 2002, http://www.epa.gov/oust/mtbe/LL42Analytical.pdf

17.0 TABLES, DIAGRAMS, FLOWCHARTS, AND VALIDATION DATA

The pages to follow contain the tables and figures referenced by this method.


TABLE 1

PURGE-AND-TRAP OPERATING PARAMETERS

_________________________________________________________________________

Analysis Method 8015 8021/8260

_________________________________________________________________________

Purge gas N2 or He N2 or He

Purge gas flow rate (mL/min) 20 40

Purge time (min) 15.0 ±0.1 11.0 ±0.1

Purge temperature (EC) Ambient2 Ambient2

Desorb temperature (EC) 180 180

Backflush inert gas flow (mL/min) 20-60 20-601

Desorb time (min) 1.5 4_________________________________________________________________________

1 The desorption flow rate for Method 8021 with a wide bore capillary column will optimize atapproximately 10 to 15 mL/minute.

2 Purge temperature is 80EC for Methods 8015 and 8260 when analyzing for TBA, TAA orother fuel oxygenate alcohols.


TABLE 2

QUANTITY OF METHANOL EXTRACT REQUIRED FOR ANALYSIS OF HIGH-CONCENTRATION SOILS/SEDIMENTS

___________________________________________________________________

Approximate Volume ofConcentration Range Methanol Extracta

___________________________________________________________________

500-10,000 µg/kg 100 µL 1,000-20,000 µg/kg 50 µL 5,000-100,000 µg/kg 10 µL25,000-500,000 µg/kg 100 µL of 1/50 dilutionb

___________________________________________________________________

Calculate appropriate dilution factor for concentrations exceeding this table.

a The volume of methanol added to 5 mL of water being purged should be kept constant.Therefore, add to the 5 mL syringe whatever volume of methanol is necessary to maintaina volume of 100 µL added to the syringe.

b Dilute an aliquot of the methanol extract and then take 100 µL for analysis.


FIGURE 1EXAMPLE OF PURGING DEVICE


FIGURE 2EXAMPLE OF TRAP PACKINGS AND CONSTRUCTION

TO INCLUDE DESORB CAPABILITY


FIGURE 3SCHEMATIC OF TYPICAL PURGE AND TRAP DEVICE

PURGE MODE


FIGURE 4SCHEMATIC OF TYPICAL PURGE AND TRAP DEVICE

DESORB MODE

METHOD 5030C - PURGE-AND-TRAP FOR AQUEOUS SAMPLES · PDF file5030C - 1 Revision 3 May 2003...

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